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A278506
Inverse permutation to A278505.
4
1, 2, 3, 4, 5, 7, 6, 11, 9, 16, 8, 22, 10, 29, 14, 37, 12, 46, 15, 56, 13, 67, 17, 79, 20, 92, 21, 106, 23, 121, 27, 137, 18, 154, 30, 172, 19, 191, 28, 211, 38, 232, 35, 254, 24, 277, 47, 301, 36, 326, 26, 352, 57, 379, 25, 407, 31, 436, 68, 466, 44, 497, 45, 529, 80, 562, 54, 596, 39, 631, 93, 667, 34, 704, 32
OFFSET
1,2
FORMULA
a(n) = (1/2) * ((c+r)^2 - r - 3*c + 2), where c = A278539(n), and r = A278538(n).
PROG
(Scheme) (define (A278506 n) (let ((row (A278538 n)) (col (A278539 n))) (* (/ 1 2) (- (expt (+ row col) 2) row col col col -2))))
CROSSREFS
Inverse: A278505.
Cf. also A278504, A278512.
Sequence in context: A266637 A370496 A278505 * A255546 A358874 A080688
KEYWORD
nonn
AUTHOR
Antti Karttunen, Nov 23 2016
STATUS
approved